AD80, a multikinase inhibitor, exhibits antineoplastic effects in acute leukemia cellular models targeting the PI3K/STMN1 axis

[Molecular Mechanism of circVRK1 Regulating the Proliferation and Apoptosis of Acute Lymphoblastic Leukemia KOCL44 Cells by Targeting miR-4428]

Objective

To elucidate the role of circVRK1 and its interaction with miR-4428 in regulating proliferation and apoptosis in acute lymphoblastic leukemia (ALL) cells.

Methods

KOCL44 ALL cells were cultured in vitro, and experimental groups included pcDNA, pcDNA-circVRK1, anti-miR-NC, anti-miR-4428, si-NC, si-circVRK1, pcDNA-circVRK1+miR-NC, and pcDNA-circVRK1+miR-4428. The expression levels of circVRK1 and miR-4428 were detected using qRT-PCR. CCK-8 assays and flow cytometry were used to assess cell proliferation and apoptosis, respectively. The dual luciferase reporter assays were employed to investigate the interaction between circVRK1 and miR-4428, with groups categorized as WT-circVRK1+miR-NC, WT-circVRK1+miR-4428, MUT-circVRK1+miR-NC, and MUT-circVRK1+ miR-4428. Western blotting was utilized to detect the expression levels of Ki-67, cleaved caspase-3, and cleaved caspase-9 proteins.

Results

Compared to the pcDNA group, circVRK1 expression was up-regulated in the pcDNA-circVRK1 group (P<0.05). Compared to transfection with pcDNA or anti-miR-NC, transfection with pcDNA-circVRK1 or anti-miR-4428 led to decreased cell viability and Ki-67 protein levels in KOCL44 cells (P<0.05), and increased apoptosis rates and levels of cleaved caspase-3 and cleaved caspase-9 (P<0.05). circVRK1 was found to negatively regulate miR-4428 expression, with this effect observed only in the WT-circVRK1 group. miR-4428 levels were lower in the pcDNA-circVRK1 group compared to the pcDNA group (P<0.05) and higher in the si-circVRK1 group compared to the si-NC group (P<0.05). Co-transfection with pcDNA-circVRK1+miR-4428 resulted in increased cell viability (P<0.05) and Ki-67 expression (P<0.05), and decreased apoptosis rates and levels of cleaved caspase-3 and cleaved caspase-9 (P<0.05) compared to co-transfection with pcDNA-circVRK1+miR-NC.

Conclusion

Overexpression of circVRK1 reduces the proliferation ability of acute ALL cells and induces cell apoptosis by downregulating miR-4428 expression.

Modulating in vitro lung fibroblast activation via senolysis of senescent human alveolar epithelial cells

Idiopathic pulmonary fibrosis (IPF) is an age-related disease with poor prognosis and limited therapeutic options. Activation of lung fibroblasts and differentiation to myofibroblasts are the principal effectors of disease pathology, but damage and senescence of alveolar epithelial cells, specifically type II (ATII) cells, has recently been identified as a potential trigger event for the progressive disease cycle. Targeting ATII senescence and the senescence-associated secretory phenotype (SASP) is an attractive therapeutic strategy; however, translatable primary human cell models that enable mechanistic studies and drug development are lacking. Here, we describe a novel system of conditioned medium (CM) transfer from bleomycin-induced senescent primary alveolar epithelial cells (AEC) onto normal human lung fibroblasts (NHLF) that demonstrates an enhanced fibrotic transcriptional and secretory phenotype compared to non-senescent AEC CM treatment or direct bleomycin damage of the NHLFs. In this system, the bleomycin-treated AECs exhibit classical hallmarks of cellular senescence, including SASP and a gene expression profile that resembles aberrant epithelial cells of the IPF lung. Fibroblast activation by CM transfer is attenuated by pre-treatment of senescent AECs with the senolytic Navitoclax and AD80, but not with the standard of care agent Nintedanib or senomorphic JAK-targeting drugs (e.g., ABT-317, ruxolitinib). This model provides a relevant human system for profiling novel senescence-targeting therapeutics for IPF drug development.

STMN1 promotes cell malignancy and bortezomib resistance of multiple myeloma cell lines via PI3K/AKT signaling

BACKGROUND

This study investigates the biological functions of Stathmin1 (STMN1) involving drug resistance and cell proliferation in multiple myeloma (MM) and its related mechanisms.

METHODS

Bone marrow aspirates were collected from 20 MM patients, and the bone marrow mononuclear cells (BMMCs) were separated by Ficoll-Hypaque density gradient centrifugation. Blood samples of 20 patients with monoclonal gammopathy of undetermined significance (MGUS) and 20 healthy donors were collected. Normal plasma cells sorted from the peripheral blood of MGUS patients and healthy subject as controls. Two bortezomib (BTZ)-resistant MM cell lines were established, namely NCI-H929/BTZ and KM3/BTZ cells, and then transfected with lentiviruses packaging sh-STMN1 to knock down STMN1 level in BTZ-resistant cells. Expression of STMN1 was assessed by RT-qPCR and western blotting. CCK-8 assays were performed to assess 50% growth inhibition (IC50) values. Green fluorescent protein in BTZ-resistant cells infected with lentiviruses was observed by fluorescence microscopy. Cell viability, proliferation, cell cycle, and apoptosis were evaluated through MTT assays, colony formation assays, flow cytometry analyses, and TUNEL staining.

RESULTS

STMN1 was upregulated in MM cells and bone marrow aspirates of MM patients. Additionally, STMN1 depletion attenuated BTZ resistance in MM cells. Moreover, downregulation of STMN1 limited the malignant phenotypes of BTZ-resistant cells. Mechanistically, the PI3K/Akt signaling was inactivated by STMN1 downregulation in BTZ-resistant cells.

CONCLUSION

STMN1 silencing inhibits cell proliferation and BTZ resistance in MM by inactivating the PI3K/Akt signaling.

The Multikinase Inhibitor AD80 Induces Mitotic Catastrophe and Autophagy in Pancreatic Cancer Cells

Significant advances in understanding the molecular complexity of the development and progression of pancreatic cancer have been made, but this disease is still considered one of the most lethal human cancers and needs new therapeutic options. In the present study, the antineoplastic effects of AD80, a multikinase inhibitor, were investigated in models of pancreatic cancer. AD80 reduced cell viability and clonogenicity and induced polyploidy in pancreatic cancer cells. At the molecular level, AD80 reduced RPS6 and histone H3 phosphorylation and induced γH2AX and PARP1 cleavage. Additionally, the drug markedly decreased AURKA phosphorylation and expression. In PANC-1 cells, AD80 strongly induced autophagic flux (consumption of LC3B and SQSTM1/p62). AD80 modulated 32 out of 84 autophagy-related genes and was associated with vacuole organization, macroautophagy, response to starvation, cellular response to nitrogen levels, and cellular response to extracellular stimulus. In 3D pancreatic cancer models, AD80 also effectively reduced growth independent of anchorage and cell viability. In summary, AD80 induces mitotic aberrations, DNA damage, autophagy, and apoptosis in pancreatic cancer cells. Our exploratory study establishes novel targets underlying the antineoplastic activity of the drug and provides insights into the development of therapeutic strategies for this disease.

STNM1 in human cancers: role, function and potential therapy sensitizer

STMN1 belongs to the stathmin gene family, it encodes a cytoplasmic phosphorylated protein, stathmin1, which is commonly observed in vertebrate cells. STMN1 is a structural microtubule-associated protein (MAP) that binds to microtubule protein dimers rather than microtubules, with each STMN1 binding two microtubule protein dimers and preventing their aggregation, leading to microtubule instability. STMN1 expression is elevated in a number of malignancies, and inhibition of its expression can interfere with tumor cell division. Its expression can change the division of tumor cells, thereby arresting cell growth in the G2/M phase. Moreover, STMN1 expression affects tumor cell sensitivity to anti-microtubule drug analogs, including vincristine and paclitaxel. The research on MAPs is limited, and new insights on the mechanism of STMN1 in different cancers are emerging. The effective application of STMN1 in cancer prognosis and treatment requires further understanding of this protein. Here, we summarize the general characteristics of STMN1 and outline how STMN1 plays a role in cancer development, targeting multiple signaling networks and acting as a downstream target for multiple microRNAs, circRNAs, and lincRNAs. We also summarize recent findings on the function role of STMN1 in tumor resistance and as a therapeutic target for cancer.

Indolyl-chalcone derivatives trigger apoptosis in cisplatin-resistant mesothelioma cells through aberrant tubulin polymerization and deregulation of microtubule-associated proteins

Introduction

Malignant pleural mesothelioma (MPM) is a neoplasm with dismal prognosis and notorious resistance to the standard therapeutics cisplatin and pemetrexed. Chalcone derivatives are efficacious anti-cancer agents with minimal toxicity and have, therefore, gained pharmaceutical interest. Here, we investigated the efficacy of CIT-026 and CIT-223, two indolyl-chalcones (CITs), to inhibit growth and viability of MPM cells and defined the mechanism by which the compounds induce cell death.

Methods

The effects of CIT-026 and CIT-223 were analyzed in five MPM cell lines, using viability, immunofluorescence, real-time cell death monitoring, and tubulin polymerization assays, along with siRNA knockdown. Phospho-kinase arrays and immunoblotting were used to identify signaling molecules that contribute to cell death.

Results

CIT-026 and CIT-223 were toxic in all cell lines at sub-micromolar concentrations, in particular in MPM cells resistant to cisplatin and pemetrexed, while normal fibroblasts were only modestly affected. Both CITs targeted tubulin polymerization via (1) direct interaction with tubulin and (2) phosphorylation of microtubule regulators STMN1, CRMP2 and WNK1. Formation of aberrant tubulin fibers caused abnormal spindle morphology, mitotic arrest and apoptosis. CIT activity was not reduced in CRMP2-negative and STMN1-silenced MPM cells, indicating that direct tubulin targeting is sufficient for toxic effects of CITs.

Discussion

CIT-026 and CIT-223 are highly effective inducers of tumor cell apoptosis by disrupting microtubule assembly, with only modest effects on non-malignant cells. CITs are potent anti-tumor agents against MPM cells, in particular cells resistant to standard therapeutics, and thus warrant further evaluation as potential small-molecule therapeutics in MPM.

Survivin Small Molecules Inhibitors: Recent Advances and Challenges

Survivin, as a member of the inhibitor of apoptosis proteins (IAPs) family, acts as a suppressor of apoptosis and plays a central role in cell division. Survivin has been considered as an important cancer drug target because it is highly expressed in many types of human cancers, while it is effectively absent from terminally differentiated normal tissues. Moreover, survivin is involved in tumor cell resistance to chemotherapy and radiation. Preclinically, downregulation of survivin expression or function reduced tumor growth induced apoptosis and sensitized tumor cells to radiation and chemotherapy in different human tumor models. This review highlights the role of survivin in promoting cellular proliferation and inhibiting apoptosis and summarizes the recent advances in and challenges of developing small-molecule survivin inhibitors.

AD80, a multikinase inhibitor, as a potential drug candidate for colorectal cancer therapy

AIMS

Colorectal cancer (CRC) is a very heterogeneous disease. One of its hallmarks is the dysregulation of protein kinases, which leads to molecular events related to carcinogenesis. Hence, kinase inhibitors have been developed and are a new strategy with promising potential for CRC therapy. This study aims to explore AD80, a multikinase inhibitor, as a drug option for CRC, with evaluation of the PI3K/AKT/mTOR and MAPK (ERK1/2) status of CRC cells' panel and the cytotoxicity of AD80 in those cells, as well as in normal colon cells.

MAIN METHODS

Cellular and molecular mechanisms, such as clonogenicity, cell cycle, morphology, protein, and mRNA expression, were investigated in CRC cells after AD80 exposure.

KEY FINDINGS

Results show that PI3K/AKT/mTOR and MAPK signaling pathways are upregulated in CRC cellular models, with increased phosphorylation of mTOR, P70S6K, S6RP, 4EBP1, and ERK1/2. Hence, AD80 selectively reduces cell viability of CRC cells. Therefore, the antitumor mechanisms of AD80, such as clonogenicity inhibition (reduction of colony number and size), G₂/M arrest (increased G₂/M population, and CDKN1B mRNA expression), DNA damage (increased H2AX and ERK1/2 phosphorylation, and CDKN1A, GADD45A mRNA expression), apoptosis (increased PARP1 cleavage, and BAX, PMAIP1, BBC3 mRNA expression) and inhibition of S6RP phosphorylation were validated in CRC model.

SIGNIFICANCE

Our findings reinforce kinases as promising cancer therapeutic targets for the treatment of colorectal cancer, suggesting AD80 as a drug candidate.

STMN1 is highly expressed and contributes to clonogenicity in acute promyelocytic leukemia cells

Stathmin 1 (STMN1) is a microtubule-destabilizing protein highly expressed in hematological malignancies and involved in proliferation and differentiation. Although a previous study found that the PML-RARα fusion protein, which contributes to the pathophysiology of acute promyelocytic leukemia (APL), positively regulates STMN1 at the transcription and protein activity levels, little is known about the role of STMN1 in APL. In this study, we aimed to investigate the STMN1 expression levels and their associations with laboratory, clinical, and genomic data in APL patients. We also assessed the dynamics of STMN1 expression during myeloid cell differentiation and cell cycle progression, and the cellular effects of STMN1 silencing and pharmacological effects of microtubule-stabilizing drugs on APL cells. We found that STMN1 transcripts were significantly increased in samples from APL patients compared with those of healthy donors (all p < 0.05). However, this had no effect on clinical outcomes. STMN1 expression was associated with proliferation- and metabolism-related gene signatures in APL. Our data confirmed that STMN1 was highly expressed in early hematopoietic progenitors and reduced during cell differentiation, including the ATRA-induced granulocytic differentiation model. STMN1 phosphorylation was predominant in a pool of mitosis-enriched APL cells. In NB4 and NB4-R2 cells, STMN1 knockdown decreased autonomous cell growth (all p < 0.05) but did not impact ATRA-induced apoptosis and differentiation. Finally, treatment with paclitaxel (as a single agent or combined with ATRA) induced microtubule stabilization, resulting in mitotic catastrophe with repercussions for cell viability, even in ATRA-resistant APL cells. This study provides new insights into the STMN1 functions and microtubule dynamics in APL.